Pipe-threading die



H. W. SMITH PIPE `THREADING DIE Filg-d May 28. 1923 April ze, 1927. I 1,525,830

FIG. 1

mvEN'roR 3/ Patented Apr. 26, 1927.

UNITED STATES HOV/ARD W. SMITH, OF ELLWOOD CITY, PENNSYLVANIA.

PIPE-THREADING DIE.

Application filed May 28,

My invention relates to dies 'for threading pipe and tor similar purposes, and its object is to provide au improved threading die which shall be capable ot cutting long, tapered threads with the use ot i'elati\'ely short chasers.

1n cutting tapered pipe threads it is necessary that the chasers in the die be at least as long, with a little to spare, as the thread that is to be cut. For very long threads it has heretofore been necessary to employ correspondingly long chasers, and the hardening of such chasers is a difficult matter on account of the fact that they tend to change their shape. One harmful result ot this, among others, is that the pitch of the thread in such a chaser is not accurate.

According to my present invention I provide pipe-threading dies adapted ttor cutting long, tapered threads without the use oit unusually long chasers, and in a manner which Will allow any inequalities in the thread to he easily corrected. I accomplish this result by providing a ring which supports the chasers in grooves which are so ai ranged that short chasers maybe inserted tlierein'and will be held rigidly in the proper position to cut threads that are longer than the length of any one oi the chasers.

1n one arrangement for this purpose, l provide the supporting ring with a central groove and with grooves for receiving the chasers extending laterally trom the central groove and staggered so that the sides ot' the grooves torni seats tor the ends ot the chasers. In another construction tor the same general purpose, I split the supporting ring centrally and provide grooves tor the chasers which extend across the ring sec-- tions. In this construction, the chasers are preferably staggered as in the arrangement Where a central groove is provided in the supporting ring. it desired, however, the split ring sections may be so arranged that the chaser grooves are in lino Vwith each other, in which case the sl'iort chasers are arranged end to end with their inner ends in contact.

Another feature ot my invention consists in providing fewer chasers on the back row than in the front row. The chasers do their heaviest work at the :trout ot the die Where the cut begins, and the Work ot cutting the rear portions ot the threadsy may be done With only halt as many chasers as are necessary in cutting the t'ront portions ot the 1923. Serial N0. 641,987'.

threads. This arrangement is intended to loe used only for the larger sizes of pipe and not 'for smaller sizes where the total number ot chasers in an ordinary die is six or less.

In the accompanying drawing, F 1 is a side elevational view ot a ring die supported in an expanding'shell and provided with chasers arranged according to my present invention; Fig. 2 is a vertical sectional view taken through the construction oi Fig. 1 and substantially on the line 22, Fig. 1; Fig. 3 is a. vertical sectional vien7 taken through a modiiied construction, and Fig. d is a vertical sectional view showing another modiied construction. l

in Fig. 1 ot the drawing the numerals El and 3 indicate the upper and lower semicircular halves ot' an expanding shell which are pivoted at one end upon pivot-bolts d connected by links The expanding shell is opened and closed on side opposite the pivot-bolts i by means ot a vertical screw G having right and lett threads extending through screw-thread openings which are formed in round pins 7 that are received in horizontal openings in projections 8 at the ends ot the sections 2 and 3. This arrangement permits the screw 6 to engage the pins or round nuts 7, Without binding, in all angular positions ot the die sections, the tivo halves ot the expanding shell being tree to rotate around the pins 7 whenever the dies are opened or closed, A handle 9 is secured to the upper end of the screw (i, and an auxiliary screw 10 and a nut 11 may be provided for iixing the adjusted position ot' the expanding shell.

lVithin the expanding shell is a removable ring die consisting ot two sections 12 each of which tits into its halt of the expanding shell and is removably secured therein by means ot a guide pin 13 and a bolt 1li. rlhc guide pin 13, as shown inFig. 1, is driven from the inside in a hole in the expanding shell and is riveted on .the outside. The ring dies are thus readily removable.

As shown in Fig. 2, the ring-die sections are provided with central grooves 15 Aand with countersunk grooves 16 at their edges, the latter grooves being arranged to receive clamping rings 17 whichv are secured to the rinor sections 12 by means of screiv-bolts 18.

hasers y19 are held in radial grooves which extend from the central grooves 15 to the outer edges of the ring sections. As

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shown in Fier. 2 the chasers 19 are staggered so that each chaser may extend across the groove and rest against the opposite side ot' this groove. The clamping plates 17 clamp the chasers 19 rigidly in position` It will thus be seen that effective cutting edges are provided across the entire distance between the clamping plates 17, and this result is accomplished by comparatively short chasers. It will also be seen that any inequalities in the thread which may be produced with an imperfect ehaser may be readily corrected by replacing the particular chaser section which is at fault.

In the construction shown in Fig. 3, the ring-dic sections are split centrally instead of being formed with central grooves. The upper and lower sections oi the ring-die are indicated at 20 and Q1, respectively, and are split on the line 22, the separate portions of the ring-die members beingl connected to- A gether by means ot bolts Q3.

Chipgrooves Qt are formed in the com blned ring-die sections and short chasers are received in slots that are formed in the ehip-grooves 24. The chasers shown in Fig. 3 are somewhat shorter than the width ot the ring-die sections and are held in position by means of set-screws E2G which extend through threaded openings in the clamping rings 2G. Two pairs ot the setscrews 2G are shown in Fig. 3, the remaining set-screws being omitted i'or the sake of clearness.

lt. will be observed that the die shown in Fig. B has one halt as many chasers on the lett or back row as on the right or front row. As stated above, the chasers do their heaviest work at the 'front end where the cut begins and fewer chasers in the back row are sufiicient. rl`he clampingl rings are clamped in position by means ot screwbolts 2?.

The inodilied construction shown in Fig. yl dill'ers 'from that shown in Fig. 3` in that the chaser sections are arranged end to end instead of being staggered, and are equal in number on both sides oi" the ring-die. The upper and lower sections ot' the ring-die are indicated at' 30 and 31, respectively and are both split on the lin-e 32, the separate portions of the ring-die members being con nected together by means ot bolts 33.

Short chasers 34 are received in grooves formed end to end in the ring-die sections, and are clamped in place by means ot' clampu ing rings 36 and bolts 3T similar to the corresponding parts shown in Figs; 1 to 3.

In assembling this form of my device, the clamping rings 36 are first secured to the separate portions of the ring-die sections, the chasers are placed in their grooves, and the separate portions of the die-sections are `secured together by means of the bolts 33,

after which the clamping rings 36 are tightened by means of the screw-bolts 3T to rigidly clamp the chasers,.

My invention is not restricted to the use of two rows or' chasers since the dies may be readily built with the total length of the chasers divided into three or more sections instead of two.

It will also be understood that my invention is not restricted to the other details of construction herein shown, since these may be modilied in any desired manner within the scope ot the appended claims.

I claim as my invention:

1. A threading die comprising a circu larly curved holder having an internal groove iormed parallel to the sides thereof, and chasers shorter than the width ol' said holder, said chasers being disposed in transverse grooves which extend from the sides ol said holder to the said central groove and which are staggered with respect to each other.

A threading die comprising a circulai-ly curved holder having an internal central groove formed parallel to the sides thereof, and chasers shorter than the width ot' said holder, said chasers being disposed in transverse grooves which extend from the sides ot' said holder to the said central groove and which are staggered with respect to each other, and side members for clamping the said chasers against the opposite walls o1 said central groove.

3. A threading die comprising a shell split dian'ietrically to forni semi-circular sections which are pivotally adjustable, semi-circular ring sections removably secured within said shell sections, each oi said ring sections having an internal central groove and having lateral grooves extending between said central groove and the sides ot' said ring sections, chasers disposed in `said lateral grooves, each otI said chasers extending between the open end o'l" its groove and the opposite wall oi said central groove, and clamping members secured to the sides et said ring sections.

In testimony whereof I, the said Howaan IV. SMITH, have hereunto set my hand.

HOWARD IV. SMITH. 

